Method of form dressing of abrasive wheels



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Jan. 17, 1956 METHOD OF FORM DRESSING OF' ABR-ASIVE WHEELS United States Patent O METHOD OF FORM DRESSING F ABRASIVE WHEELS Application March 20, 1952, Serial No. 277,562

4 claims. (cl. 51-283) The present` invention is concerned with a method for form dressing abrasive wheels, and to an apparatus employed in the practice of that method.

One of the more common methods for providing the periphery of an abrasive wheel with a desired profile involves the operation known as crush dressing. In this type of wheel dressing the periphery of the abrasive wheel is brought into pressure contact with a form having the reverse of the configuration desired in the wheel periphery, the form having a facing composed of hard metal or compounds such as silicon carbide, tungsten carbide, and the like. As the abrasive wheel is rotated, the hard surface of the form presses into the periphery of the wheel, thereby crushing the vitriiied binder matrix in which the abrasive grid particles are embedded, as well as crushingto some extent the abrasive grit particles at the periphery of the wheel. Abrasive wheels bonded by resinoids, rubber, and shellac do not lend themselves to crush dressing because of their resilient nature. One of the `difficulties with the crush grinding operation of the type described is the fact that it is inherently incapable of finishing a grinding wheel to closely limited tolerances, even though the form itself may have the correct dimensional tolerances. Usually, the crush dressing operation has to be followed by a finishing dressing operation in order to bring the shape of the grinding wheel peripherywithin the dimensional tolerances required.

Furthermore, the pressure, the pressures involved in crush dressing, usually being on the order of 400 to 500 pounds per square inch put a substantial stress on the spindle carrying the abrasive wheel, so that frequently, the abrasive wheel must be crush dressed on a spindle other than that which carries the wheel during the regu lar dressing operation.

An object of the present invention is to provide an improved method for form dressing of abrasive wheels.

Still another object of the present invention is to provide a method for abrading, rather than crush dressing a grinding wheel to provide the grinding wheel with a contoured surface within close dimensional tolerances.

Still another object of the present invention is to provide a form dressing assembly for the form dressing of grinding wheels in which the form dressing time is substantially reduced.

Another object of the invention is to provide an improved assembly for the form dressing of grinding wheels employing a novel form dressing tool.

Other objects and features of the present invention will be apparent to those skilled in the art from the following description of the attached sheet of drawings in which:

Figure l is a view with parts in elevation of the form dressing assembly; and

Figure 2 is a fragmentary side view with parts in elevation, of the assembly of Figure l.

As shown on the drawings:

Reference numerals and 11 denote two grindingwheels the axes of rotation of which are parallel to each other, and which are mounted in the same plane of rotation. The wheels as shown are mounted in a vertical plane but may lie in a horizontal or other plane. The wheels 10 and 11 may be composed of abrasive particles embedded in any of the common materials, including vitritied composition, resinoids, rubber, or shellac, as the method of the invention accurately dresses all these types of Wheels. The upper grinding wheel 10 is supported on a spindle 12 journaled in a bearing 13. A pulley 14 carried by the spindle 12 drives the wheel 10 by means of a belt 15 associated with a drive motor 16. The grinding wheel structure as well as the motor 16 are supported on an L-shaped bracket 17. The shorter leg 18 of the L-shaped bracket has a tongue formed therein received within a channel 20 of a vertical support 21. The leg 18 has an internally threaded bore 23 which receives a threaded rod 24, the latter being supported from the support 21 by means of a pair of vertically spaced bearings 25 and 26. A hand crank 28 secured to the threaded rod 24 is provided for rotating the rod 24, and by virtue of the engagement of the threads of the rod 24 with the threaded bore 23 of the leg 18, rotation of the hand crank 28 moves the L-shaped support bracket 17, the grinding wheel 10, and the motor 16 into an adjusted vertical position.

The grinding wheel 11 is mounted in the same manner as that employed for mounting the grinding Wheel 1t). A spindle 30 carrying the grinding wheel 11 is driven by means of a pulley 31, a belt 32, and a motor 33 at a desired angular velocity. Preferably, the grinding wheels 10 and 11 are driven in opposite directions but at the same angular velocity. i The motor 33 and the grinding wheel 11 are mounted on an L-shaped support bracket 35, the latter having an internally threaded bore 36 in the shorter leg thereof Which engages the threads of a threaded rod 37. A hand crank 40 is provided to enable vertical adjustment of the L-shaped support bracket 35, and hence the vertical position of the grinding Wheel 11.

The form dressing tool of the present invention is best illustrated in Figure 2. The tool consists of a tool body 42 having oppositely contoured nonplanar abrasive surfaces 43. The configuration of the abrasive surfaces 43 will be the opposite from that desired in the profile of the grinding wheels to be dressed. Many different types of cutting tools can be employed for the purposes of the present invention, as, for example, a tool formed by powder metallurgy from a mixture of tungsten and tungsten carbide and having finely divided diamond particles embedded in the surfaces 43. The size of the particles is quite small, being on the order of 400 particles per carat.

The cutting tool body 42 is secured tol a carrier 45 by means of a pair of spaced securing bolts 46. The carrier 45 is also provided with a tongue which is slidably received within a channel 48 of a guideway 49. ln order to distribute the abrading action over the :full length of the abrasive surfaces 43, the carrier 45 is reciprocated tangentially to the peripheries of the wheels 10 and 11 during rotations of the wheels, as shown in Figure l. The carrier 45 is carried by a rod 51 associated with a hydraulic cylinder 52. A plurality of uid inlet means 53 and 54 are provided in the cylinder 52 for periodically reciprocating a piston (not shown) secured to the end of the rod 51 and reciprocable within the cylinder 52.

In the form dressing of the grinding wheels 10 and 11, the wheels are preferably rotated in opposite directions by means of their associated motors 16 and y33, but at the same angular velocity. As the grinding wheels 10 and 11 are rotated, pressurized fluid is introduced alternately into the fluid inlet means 53 and 54 associated with the hydraulic cylinder 52, thereby causing reciprocation of tlc' carrier 45V and the 00142 associated therewith. The spacing of' the wheels ltrand 11v is4 sutl'ic'i'en't to engageV the abrasive covered surfaces 43 and 44 of the dressing v t,ool42toy afford an abrading contact between theperiphthe' tool dueto' the differential surface speeds,vthe pressure contact between the Wheels andthe tool being less thancrushirgipes'sre. The tool 42 is reciprocated back and forth" in'a directionr tangential to the peripheries-of both the' vvlieels 1`0 and 11 in as many passes as necessary to abrade tlie'p'e'riphery of the rapidlyl rotating grinding Wheels and 1"1 into a configuration which is the opposite of the configuration of' the abrading surfaces 43 and 44.

The abrading action ofthehtool, in contrast to the crushing action. of crush dressingV tools, provides an accurate form dressing of the periphery of the lgrinding wheels to within close dimensional` tolerances. The tools' ofv the present invention also provide a faster form dressing time thanV has heretofore been customary, and have the furtherradvaritage that the useful life of the dressing y too'lhis considerably longer than that possessed by other types of form dressing tools.

It will be understood that modifications and variations may be elected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. The method of form dressing a pair of abrasive wheels composed of abrasive grit in a matrix of a binder, which comprises moving said pair of wheels laterally tot ward each other, interposing between the peripheries of said wheels a pair of oppositely facing diamond particle abrasive surfaces of predetermined contour, rotating said wheels while in pressure contact with said surfaces, the pressure of said contact being insuflcient to crush said binder and moving said abrasive surfaces relative to the surfaces of said wheels tangentially thereof in abrading contact with the peripheries of said wheels to abrade the wheelsy to the reverse contour of said abrasive surfaces.

2; ,The method. of form dressing a pair of abrasive wheels composed of abrassive grit in a matrix of a binder,

3. The methodY of form. dressing a pair of abrasive wheels which comprises` rotatingv saidwheels at the same rangular velocity and in the sameV plane. of rotation,k 'reciprocating a pair of opposed diamond particle abrasive surfaces tangentially toy bothI of 'saidwheels'vvith said surfaces in abrading contactbutlessnthan crushing pressure contact with the peripheries of both of said wheels to abrade the wheels to the reverse contour of said abrasive surfaces.

4. The method of form dressinga pair of abrasive wheels which comprises rotating the wheelsaty the same angular velocity and inthe samey plane of rotation, reciprocating a pair of identicalY opposed diamond particle abrasive surfaces tangentially to both of said Vwheels with saidv surfaces in abrading contact but less than crushing pressure. contact with the peripheres` of both of said wheels to abrade the 'wheels to the reverse contour of said abrasive surfaces and to provide the wheels with identical surfaces.

References Cited inthe tile of this patent UNITED STATES'PATENTS 1,896,533 Vuillemier Feb. 7, 1933 2,105,896 Stubbs Jari.v 18, 1938 2,120,570 reame June 14, 1938 2,210,039 Petrie Aug. 6, 1940y 2,281,420 Drader I Y.Y Apr. 28, 1942 2,333,304 Ernst NOV. 2, 1943 2,456,762 WilSOn Dec. 21, 1948 2,458,605v Kirin Ian. 11, 1949 2,477,418 Polk July 26, 1949 2,578,531 Flanders Dec. 11, 1951 

